1. Field of the Invention
The present invention relates generally to a safety shift-lock device for an operational range selector of an automatic power transmission of an automotive vehicle, which locks the selector at a predetermined operational range position, e.g., P(park) position for disabling shifting of the selector unless a predetermined safety assuring condition is established.
2. Description of the Prior Art
In recent years, it has become popular to provide a safety shift-lock device for an operational range selector for an automotive automatic power transmission in order to prevent a vehicle from unexpected running upon unconsciously or carelessly shifting the selector from P range position from driving range position, such as D (automatic shift) range position, R (reverse) range position, 1 (first hold) range position, 2 (second hold) range position and so forth. Typically, such a safety shift-lock device is designed to establish shift-locking at P range position of the selector and permit to shift to other range position when an ignition switch is maintained at ON position and a foot brake is applied. This arrangement is successful in prevention of unexpected run of the vehicle upon starting up of the vehicle. Japanese Utility Model First (unexamined) Publication (Jikkai) Showa 60-185750 discloses a floor-shift type selector for the automatic power transmission, which selector is associated with a safety shift-lock device for locking the selector at the P range position.
In the shift-lock device proposed in the Japanese prior publication there is a problem or drawback in liability for a possibility of damaging actuator pin which is active for establishing shift-locking, when relatively great input force is exerted on the selector while the locking engagement is established. When the actuator pin is deformed by the externally applied operation force for the selector, the shift-lock tends to become inoperative, or in the worse case, shift-lock becomes impossible to release. For preventing damaging of the actuator pin, it becomes necessary to make the actuator pin thicker and
stronger However, such increased size of actuator pin naturally leads increasing of the bulk size of a lock actuator resulting in higher production cost, greater weight and lesser freedom in orientation of the actuator.